Performance – IT Blog

Taskset – bind process to CPU cores

By default, processes use all the processor cores, but sometimes it is necessary to release the 0 core, which is usually the most loaded, or assign some processes only to the second CPU, etc., in this case, taskset will help.

Increase the port range net.ipv4.ip_local_port_range

There is a possibility that on a highly loaded server, such as a proxy or router, with a very large number of connections, free ports in the allocated range may run out, so you need to look at the current number used and, if necessary, increase the net.ipv4.ip_local_port_range value.

Configuring logrotate to rotate logs

Logrotate is used to control the logging system, compress log files, delete old ones, etc.
The configuration is located at /etc/logrotate.d/ and /etc/logrotate.conf.

Testing a DHCP server with dhcpperf

dhcpperf is a DHCP load testing tool.

How to change innodb_flush_method in MySQL

innodb_flush_method defines the method for flushing data from RAM to disk.

High CPU load on Cisco Nexus 3064

Once I discovered on the graphs a large burst of Multicast packets on one of the ports of the Cisco Nexus 3064 switch, while the CPU load increased to 30%, before that it was 12% with L2 traffic of 13 Gbit/s.

Migrating MySQL Directory

Once I created a raid, mounted it as a disk system partition and transferred the MySQL directory directly to it, but in this case there were drawbacks, the lost+found directory could appear, it could not be used for other data, etc., after that I began to transfer the MySQL directory not directly to the partition, but created a directory on it and transferred it to it.

How to change innodb_io_capacity in MySQL

innodb_io_capacity – determines the number of write IOPS for background InnoDB tasks, such as flushing pages from a buffer pool, etc. If the cleanup operation is lagging, then InnoDB can perform cleanup more aggressively at a higher IOPS, which is defined in the innodb_io_capacity_max variable.

Installing and configuring xt_NAT

I will give an example of installing and configuring xt_NAT on Ubuntu Server 14.04 with kernel version 4.4.0-142. xt_NAT may not work on newer kernel versions. According to the developer, it should work on Linux Kernel 3.18 and 4.1. To make it work on newer versions of the kernel, you can find patches.

Partitioning tables in MySQL

Partitioning tables in MySQL is splitting a large table into parts according to the specified criteria, which will speed up reading and writing data to it if this table contains a very large amount of data.